Liquid electro-photographic (LEP) printing uses a special kind of ink to form images on paper and other print substrates. LEP ink includes charged polymer particles dispersed in a carrier liquid. The polymer particles are sometimes referred to as toner particles and, accordingly, LEP ink is sometimes called liquid toner. LEP ink usually also includes a charge control agent, called a “charge director”, that helps control the magnitude and polarity of the charge on the particles. The LEP printing process involves placing an electrostatic pattern of the desired printed image on a photoconductor and developing the image by applying a thin layer of LEP ink to the charged photoconductor. Charged toner particles in the ink adhere to the pattern of the desired image on the photoconductor. The ink image is transferred from the photoconductor to a heated intermediate transfer member, evaporating much of the carrier liquid to dry the ink film. The ink film is then pressed on to the cooler substrate and frozen in place at a nip between the intermediate transfer member and the substrate.
The same part numbers designate the same or similar parts throughout the figures.